Hi,
There is no on-line PDF version of HtDP.
The copyright to HtDP is owned by the MIT Press. They were generous
in allowing us to put an HTML version on-line, in full, for free. In
return, they limit the on-line availability to the HTML format.
Of course, if you would like a paper copy of the book, you can find a
print version of the book very easily. Check out a bookstore. (-:
(Btw, the on-line version is generated by tex2page, the superior
alternative to tex2html.)
Shriram